JP5931672B2 - Polyimide laminate and method for producing the same - Google Patents

Description

  The present invention relates to a polyimide laminate and a method for producing the same, and more particularly to a polyimide laminate obtained by laminating a transparent polyimide layer on a support substrate and a method for producing the same.

  Display devices such as liquid crystal display devices and organic EL display devices are used for various display applications such as large displays such as televisions and small displays such as mobile phones, personal computers, and smartphones. Among these, when an organic EL display device is taken as an example, a thin film transistor (hereinafter referred to as TFT) is formed on a glass substrate, an electrode, a light emitting layer, and an electrode are sequentially laminated, and finally a glass substrate, a multilayer thin film, etc. Made with a hermetic seal.

  Here, by replacing the glass substrate with a resin substrate, it is possible to realize flexibility and a reduction in thickness and weight, thereby further expanding the application of the display device. For example, Non-Patent Documents 1 and 2 propose an organic EL display device in which highly transparent polyimide is applied to a support substrate. However, in general, resins are inferior to glass in terms of dimensional stability, transparency, heat resistance, moisture resistance, gas barrier properties, etc., and therefore, development of resins having properties similar to those of glass is currently underway.

  For example, Patent Document 1 relates to a polyimide useful as a plastic substrate for a flexible display and an invention relating to a precursor thereof, using tetracarboxylic acids containing an alicyclic structure such as cyclohexylphenyltetracarboxylic acid. It has been reported that polyimides reacted with various diamines are excellent in transparency and heat resistance.

  On the other hand, when the advantages of the resin substrate are pursued, the problem is the handleability and dimensional stability of the resin substrate itself. In other words, if the resin substrate is made into a thin film, the occurrence of wrinkles and cracks can be prevented, and the positional accuracy when forming functional layers such as TFTs and electrodes and the dimensional accuracy after forming the functional layers are increased. It becomes difficult to maintain. Therefore, in Non-Patent Document 3, a predetermined functional layer is formed on a resin substrate that is applied and fixed on glass, and then a laser is irradiated from the glass side by a method called an EPLaR (Electronics on Plastic by Laser Release) process. A method for forcibly separating a resin substrate having a functional layer from glass has been proposed.

  In Non-Patent Document 4, after applying a polyamic acid solution on glass through a release layer and curing the polyimide substrate obtained by providing a predetermined functional layer, the polyimide substrate is peeled off from the glass. A method has been proposed. In this method, the polyamic acid solution is applied in a larger area than the release layer so that the periphery of the cured polyimide substrate is directly fixed to the glass, and the periphery is left on the glass. A cut is made in the portion where the functional layer is formed, and the polyimide substrate formed through the release layer is separated from the glass.

  These technologies described in Non-Patent Documents 3 and 4 both use glass as a supporting base material, and form a functional layer on a resin substrate fixed to glass, thereby improving the handleability and dimensional stability of the resin substrate. However, there is a problem in that productivity is low because a special means is used to separate the resin substrate from the glass. That is, in the method using the EPLaR process described in Non-Patent Document 3, it takes time to separate the resin substrate from the glass, and the surface properties of the resin substrate may be adversely affected. In addition, the method described in Non-Patent Document 4 increases the number of processes and generates a region that cannot be used as a resin substrate, resulting in waste. Therefore, there is a strong demand for the development of technology that can be used by industrially contributing means while taking advantage of the advantages of the resin substrate.

  Patent Documents 2 and 3 describe inventions relating to a method for producing a polyimide film. A polyamic acid solution is applied on a polyimide layer of a metal foil provided with a predetermined polyimide layer, and heat-treated to form an imide. Although a method for producing a polyimide film that peels off the formed polyimide and suppresses appearance defects such as wrinkles and cracks is shown, the polyimide film shown here is not transparent, and polyimide is laminated. It is not described at all that this is used as a resin substrate.

JP 2008-231327 A Japanese Patent No. 4260530 JP 2011-56825 A

S. An et. Al., “2.8-inch WQVGA Flexible AMOLED Using High Performance Low Temperature Polysilicon TFT on Plastic Substrates”, SID2010 DIGEST, p706 (2010) Oishi et. Al., “Transparent PI for flexible display”, IDW’11 FLX2 / FMC4-1 E.I. Haskal et. Al. "Flexible OLED Displays Made with the EPLaR Process", Proc. Eurodisplay '07, pp. 36-39 (2007) Cheng-Chung Lee et. Al. "A Novel Approach to Make Flexible Active Matrix Displays", SID10 Digest, pp.810-813 (2010)

  Therefore, the present inventors have intensively studied a means that can use a polyimide film excellent in heat resistance and transparency as a resin substrate while ensuring handling (also referred to as handling) and dimensional stability. As a result of overlaying, a polyimide laminate having a support base on the back side of a transparent polyimide layer, the surface of the support base being formed from polyimide having a predetermined property, and the polyimide from the support base It has been found that all the problems of the prior art can be solved by making the polyimide film composed of layers separable, and the present invention has been completed.

  Therefore, the object of the present invention is to use a transparent polyimide film as a resin base material, and is excellent in handleability and dimensional stability, and can easily separate the polyimide film from the support base material. It is providing the polyimide laminated body and its manufacturing method.

（４）ポリイミド層の熱膨張係数が１５ｐｐｍ／Ｋ以下である（１）〜（３）のいずれかに記載のポリイミド積層体。
（５）ポリイミド層の厚さが３μｍ以上５０μｍ以下であり、また、支持基材の厚さが１０μｍ以上１００μｍ以下である（１）〜（４）のいずれかに記載のポリイミド積層体。
（６）支持基材から剥離した後のポリイミドフィルムの剥離面は、表面粗さＲａが１００ｎｍ以下である（１）〜（５）のいずれかに記載のポリイミド積層体。
（７）ポリイミド層の表面側に所定の機能層を形成した後、背面側の支持基材を分離して用いる（１）〜（６）のいずれかに記載のポリイミド積層体。
（８）支持基材の背面側に更に粘着層を備える（１）〜（７）のいずれかに記載のポリイミド積層体。
That is, the gist of the present invention is as follows.
(1) A polyimide laminate comprising a support base on the back side of the polyimide layer , the polyimide layer comprising a single layer or a plurality of layers, and at least the layer in contact with the support base is a fluorine-containing polyimide, and the polyimide and the transmittance at 440nm from 780nm wavelength region of the layer 70% or more, and the surface of the supporting substrate at the interface between the polyimide layer and the supporting substrate, a glass transition temperature Tg is above 300 ° C. heat-resistant polyimide The surface roughness Ra is 100 nm or less, the adhesive strength between the support substrate and the polyimide layer is 1 N / m or more and 500 N / m or less, and the polyimide film comprising the polyimide layer from the support substrate A polyimide laminate characterized in that it can be separated.
(2) The polyimide laminate according to (1), wherein the adhesive strength between the support substrate and the polyimide layer is 5 N / m or more and 300 N / m or less .
(3) The polyimide laminated body as described in (1) or (2) whose heat resistant polyimide in a support base material is a polyimide which has the following structural unit.

(4) The polyimide laminated body in any one of (1)-(3) whose coefficient of thermal expansion of a polyimide layer is 15 ppm / K or less.
(5) The polyimide laminated body in any one of (1)-(4) whose thickness of a polyimide layer is 3 micrometers or more and 50 micrometers or less, and whose thickness of a support base material is 10 micrometers or more and 100 micrometers or less.
(6) The polyimide laminate according to any one of (1) to (5), wherein the release surface of the polyimide film after peeling from the support substrate has a surface roughness Ra of 100 nm or less.
(7) The polyimide laminate according to any one of (1) to (6), wherein a predetermined functional layer is formed on the surface side of the polyimide layer, and then the support substrate on the back side is separated and used.
(8) The polyimide laminate according to any one of (1) to (7), further including an adhesive layer on the back side of the support substrate.

（12）（９）〜（11）のいずれかに記載された方法により得られたポリイミド積層体から、ポリイミド層を分離することを特徴とするポリイミドフィルムの製造方法。 (9) A method for producing a polyimide laminate comprising a support base on the back side of a polyimide layer, which is formed of a heat-resistant polyimide having a glass transition temperature Tg of 300 ° C. or higher and a surface roughness Ra of 100 nm or less. While a long support substrate having a heat-resistant polyimide surface is conveyed by a roll-to-roll process, a fluorine-containing polyamic acid resin solution is applied onto the heat-resistant polyimide surface of the long support substrate. The support substrate is heat-treated at 200 ° C. or more to imidize the polyamic acid to form a polyimide layer having a transmittance of 70% or more in the wavelength region of 440 nm to 780 nm on the support substrate. The adhesive strength between the material and the polyimide layer is set to 1 N / m or more and 500 N / m or less, and the polyimide film composed of the polyimide layer can be separated from the support substrate. Method for manufacturing a polyimide laminate and symptoms.
(10) The method for producing a polyimide laminate according to (9), wherein the heat treatment condition of the polyamic acid is within 15 minutes in the high temperature heating temperature range from the highest temperature achieved during heating to a temperature lower by 20 ° C. .
(11) The method for producing a polyimide laminate according to (9) or (10), wherein the heat-resistant polyimide forming the heat-resistant polyimide surface in the support substrate is a polyimide having the following structural units.

(12) A method for producing a polyimide film, comprising separating a polyimide layer from a polyimide laminate obtained by the method described in any one of (9) to (11).

  According to the polyimide laminate of the present invention, since a polyimide layer excellent in transparency and heat resistance is integrated with a predetermined support base material, handling property, dimensional stability, etc. can be ensured, and In addition, since the polyimide layer can be easily separated from the support base material into a polyimide film, the polyimide film can be suitably used as a resin substrate. In addition, the polyimide laminate of the present invention has high heat resistance of the laminate itself and is applicable not only in a heat treatment process at high temperature, but also has flexibility by reducing the thickness, and roll-to-roll. Since it is applicable also to the usage method conveyed by a process, it can be used suitably for manufacture of a touch panel, a display apparatus, etc.

FIG. 1 is a cross-sectional view showing an embodiment of the polyimide laminate of the present invention. FIG. 2 is a cross-sectional view showing another embodiment of the polyimide laminate of the present invention (when the polyimide layer is a plurality of layers). FIG. 3 is a cross-sectional view showing another embodiment of the polyimide laminate of the present invention (when the supporting base material layer is a plurality of layers).

Hereinafter, the present invention will be described in detail.
The polyimide laminate of the present invention comprises a polyimide layer and a supporting substrate as essential constituent members, and includes a supporting substrate 2 on the back side of the polyimide layer 1 as shown in FIG. The thickness of the polyimide layer 1 in the polyimide laminate 10 is preferably 3 μm or more and 50 μm or less. If the thickness of the polyimide layer 1 is less than 3 μm, not only the insulation performance may be insufficient when it is used as an insulating layer, but also the handling property of the polyimide film after separation from the polyimide laminate 10 is inferior. On the other hand, if it exceeds 50 μm, the flexibility and transparency of the separated polyimide film may be lowered. The thickness of the support substrate 2 is not particularly limited as long as it can be easily separated, but is preferably 10 μm or more and 100 μm or less. If the thickness of the support base material 2 is less than 10 μm, the supportability as the support base material 2 cannot be sufficiently exhibited, and the transportability and handling property may be deteriorated. If the thickness exceeds 100 μm, the product cost is disadvantageous.

  The polyimide laminate 10 of the present invention can easily separate the support substrate 2 and the polyimide layer 1. In this invention, in order to express this ease of separation, it is preferable to apply the specific member which shows either one or both of the support base material 2 and the polyimide layer 1 below.

First, the support substrate 2 used in the present invention will be described.
The support base material 2 used in the present invention has a resin layer 2a formed on the metal foil 2b as shown in FIG. 3 when the support base material 2 is made of a resin base material as shown in FIG. A composite base material is mentioned, and it is not particularly limited as long as it can be easily separated from the polyimide layer 1 and exhibits predetermined characteristics. “Separation from the polyimide layer 1 is easy” means that the adhesive strength between the support base 2 and the polyimide layer 1 is in the range of 1 N / m to 500 N / m, preferably 5 N / m to 300 N. / M or less, more preferably 10 N / m or more and 200 N / m or less. By setting the peel strength between the support substrate 2 and the polyimide layer 1 within this range, there is obtained a polyimide laminate 10 that gives a transparent polyimide film that can be produced industrially stably without defects in appearance such as wrinkles and fractures. be able to.

  The polyimide laminate 10 of the present invention can be used in the manufacture of touch panels, display devices, etc., but heat resistance may be required there. Therefore, when the support base material 2 is made of a resin base material, for example, a polyimide base material is exemplified, and when it is made of a composite base material, a laminate of metal foil and polyimide is preferred. Illustrated.

  Here, at least the surface of the support base 2 that forms an interface with the polyimide layer 1 needs to be formed of a heat-resistant polyimide having a glass transition temperature Tg of 300 ° C. or higher. If the glass transition temperature Tg of the heat-resistant polyimide on the surface of the supporting substrate is less than 300 ° C., the heat resistance as the polyimide laminate 10 is lowered and the separability from the polyimide layer 1 may be deteriorated. Further, the surface roughness Ra of the heat-resistant polyimide surface needs to be 100 nm or less. If the surface roughness Ra exceeds 100 nm, the separation property from the polyimide layer 1 is deteriorated, which not only causes deformation at the time of separation of the polyimide, but also its transparency tends to be lowered.

Next, the polyimide layer 1 which comprises the polyimide laminated body 10 of this invention is demonstrated.
The polyimide layer 1 of the polyimide laminate 10 of the present invention exhibits a transmittance of 70% or more in the wavelength region of 440 nm to 780 nm (in the present specification, when this transmittance characteristic is satisfied, it is expressed as indicating transparency) To do). Although the polyimide layer 1 is directly provided on the support substrate 2, the polyimide layer 1 may be composed of only a single layer. For example, as shown in FIG. 2, a plurality of layers (1a, 1b, It may be composed of 1c). When the polyimide layer 1 is composed of a plurality of layers, the transmittance is exhibited by the whole of the plurality of layers.

  In the polyimide laminate 10 of the present invention, the polyimide layer 1 provided on the support substrate and the surface of the support substrate 2 that forms the interface with the polyimide layer 1 are each composed of a predetermined polyimide.

式中、Ａｒ₁は４価の有機基を表し、Ａｒ₂は２価の有機基であるが、耐熱性の観点から、Ａｒ₁、Ａｒ₂の少なくとも一方は、芳香族残基であることが好ましい。 A polyimide is usually obtained by polymerizing an acid anhydride as a raw material and a diamine, and is represented by the following general formula (1).

In the formula, Ar ₁ represents a tetravalent organic group and Ar ₂ is a divalent organic group. From the viewpoint of heat resistance, at least one of Ar ₁ and Ar ₂ may be an aromatic residue. preferable.

  Here, typical acid anhydrides used as polyimide raw materials are exemplified by pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,2 ′, 3,3'-benzophenonetetracarboxylic dianhydride, 2,3,3 ', 4'-benzophenonetetracarboxylic dianhydride, naphthalene-2,3,6,7-tetracarboxylic dianhydride, naphthalene- 1,2,5,6-tetracarboxylic dianhydride, naphthalene-1,2,4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, naphthalene -1,2,6,7-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic acid bis Anhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4 , 5,8-Tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4 , 5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 1,4,5,8-tetrachloronaphthalene -2,3,6,7-tetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride, 3,3``, 4,4' '-p-terphenyltetracarboxylic dianhydride, 2,2' ', 3 , 3``-p-terphenyltetracarboxylic dianhydride, 2,3,3 '', 4 ''-p-terphenyltetracarboxylic dianhydride, 2,2-bis (2,3-di Carboxyphenyl) -propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -propane dianhydride, bis (2,3-dicarboxyphenyl) ether dianhydride, bis (2,3- Dicarboxyphenyl) methane dianhydride, bis (3.4-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarbo Cyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4 -Dicarboxyphenyl) ethane dianhydride, perylene-2,3,8,9-tetracarboxylic dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, perylene-4,5, 10,11-tetracarboxylic dianhydride, perylene-5,6,11,12-tetracarboxylic dianhydride, phenanthrene-1,2,7,8-tetracarboxylic dianhydride, phenanthrene-1,2 , 6,7-tetracarboxylic dianhydride, phenanthrene-1,2,9,10-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, pyrazine-2 , 3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, 4, 4'-oxydiphthalic dianhydride The thing etc. are mentioned, These can be used individually or in mixture of 2 or more types.

  Moreover, typical examples of the diamine used as the polyimide raw material include 4,6-dimethyl-m-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 2,4-diaminomesitylene, 4,4 ′. -Methylenedi-o-toluidine, 4,4'-methylenedi-2,6-xylidine, 4,4'-methylene-2,6-diethylaniline, 2,4-toluenediamine, m-phenylenediamine, p-phenylenediamine 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 3,3'- Diaminodiphenylmethane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3, 3'-diaminodiphenylsulfone, 3,3'- Diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-Aminophenoxy) benzene, benzidine, 3,3'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 4,4'-diamino-p- Terphenyl, 3,3'-diamino-p-terphenyl, bis (p-aminocyclohexyl) methane, bis (p-β-amino-t-butylphenyl) ether, bis (p-β-methyl-δ-amino Pentyl) benzene, p-bis (2-methyl-4-aminopentyl) benzene, p-bis (1,1-dimethyl-5-aminopentyl) benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis (β-amino-t-butyl) toluene, 2,4-diaminotoluene, m-xylene-2 , 5-diamine, p-xylene-2,5-diamine, m-xylylenediamine, p-xylylenediamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3 1,4-oxadiazole, piperazine and the like, and these can be used alone or in admixture of two or more.

特には、下記で表される構造単位を主成分とするポリイミドであるのがよい。

なお、ここで言う主成分とは、耐熱性ポリイミドを構成する構造単位の５０モル％以上を占めることを意味し、好ましくは８０モル％以上である。 Of these, the heat-resistant polyimide constituting the surface of the supporting substrate 2 that forms the interface with the polyimide layer 1 needs to have a glass transition temperature Tg of 300 ° C. or higher, preferably biphenyltetracarboxylic dianhydride. It is good that it is a polyimide whose main component is the following structural unit consisting of a product and phenylenediamine,

In particular, it is good that it is a polyimide which has the structural unit represented below as a main component.

In addition, the main component said here means occupying 50 mol% or more of the structural unit which comprises heat resistant polyimide, Preferably it is 80 mol% or more.

  On the other hand, the polyimide layer 1 on the support base material 2 in the polyimide laminate 10 of the present invention can provide a transparent polyimide layer because the above-mentioned preferable polyimide is used for the support base material 2 so that separation is easy. Although it can be used without particular limitation, if the above-mentioned preferred polyimide is not used on the surface of the support substrate or if it is desired to make separation easier, apply fluorine-containing polyimide to the layer in contact with the support substrate 2. Is preferred. This means that when the polyimide layer 1 is composed of a single layer, the polyimide is a fluorine-containing polyimide. When the polyimide layer is composed of a plurality of layers as shown in FIG. It means that the layer 1a in contact with the heat-resistant polyimide is a fluorine-containing polyimide.

〔ここで、一般式（２）又は一般式（３）におけるＲ₁〜Ｒ₈は、互いに独立に水素原子、フッ素原子、炭素数１〜５までのアルキル基若しくはアルコキシ基、又はフッ素置換炭化水素基であり、一般式（２）にあっては、Ｒ₁〜Ｒ₄のうち少なくとも一つはフッ素原子又はフッ素置換炭化水素基であり、また、一般式（３）にあっては、Ｒ₁〜Ｒ₈のうち少なくとも一つはフッ素原子又はフッ素置換炭化水素基である。〕 The fluorine-containing polyimide refers to one having a fluorine atom in the polyimide structure, and has a fluorine-containing group in at least one of an acid anhydride and a diamine which are polyimide raw materials. Such fluorinated polyimide, in the general formula (1), Ar ₂ is exemplified as those represented by the following general formula (2) or general formula (3).

[Wherein, R _{1 to} R ₈ in the general formula (2) or the general formula (3) are each independently a hydrogen atom, a fluorine atom, an alkyl group or an alkoxy group having 1 to 5 carbon atoms, or a fluorine-substituted hydrocarbon. In the general formula (2), at least one of R _{1 to} R ₄ is a fluorine atom or a fluorine-substituted hydrocarbon group, and in the general formula (3), R ₁ at least one of to R ₈ is a fluorine atom or a fluorine-substituted hydrocarbon group. ]

Preferable specific examples of R _{1 to} R ₈ include —H, —CH ₃ , —OCH ₃ , —F, —CF _3, etc., and at least one substitution in formula (2) or formula (3) group, may be between either -F or -CF _3.

Specific examples of Ar ₁ in the general formula (1) when forming the fluorine-containing polyimide include, for example, the following tetravalent acid anhydride residues.

Also, when forming a fluorine-containing polyimide, as a specific diamine residue give Ar ₂ in the general formula (1), for example, include the following.

The polyimide layer 1 has high heat resistance and preferably has a thermal expansion coefficient of 15 ppm / K or less. Among the polyimide resins exemplified above, the structural unit represented by the following formula (4) or (5) is 80 Those having a proportion of mol% or more are suitable.

  The various polyimides described above are obtained by imidizing polyamic acid. Here, the polyamic acid resin solution uses substantially equimolar amounts of diamine and acid dianhydride as raw materials in an organic solvent. It can obtain by making it react. More specifically, it is obtained by dissolving diamine in an organic polar solvent such as N, N-dimethylacetamide under a nitrogen stream, adding tetracarboxylic dianhydride, and reacting at room temperature for about 5 hours. Can do. The weight average molecular weight of the obtained polyamic acid is preferably 10,000 to 300,000 from the viewpoint of uniform film thickness during coating and mechanical strength of the resulting polyimide film. In addition, the preferable molecular weight range of a polyimide layer is also the same molecular weight range as a polyamic acid.

  When the polyimide is a polyimide according to the structure of the general formula (4) or (5), other polyimides that may be added at a ratio of less than 20 mol% at the maximum other than the polyimide are not particularly limited. Common acid anhydrides and diamines can be used. Preferred acid anhydrides include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 1,4-cyclohexanedicarboxylic acid, 1,2,3,4 -Cyclobutanetetracarboxylic dianhydride, 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, etc., and 4,4'-diaminodiphenylsulfone, trans -1,4-diaminocyclohexane, 4,4'-diaminocyclohexylmethane, 2,2'-bis (4-aminocyclohexyl) -hexafluoropropane, 2,2'-bis (trifluoromethyl) -4,4 ' -Diamino bicyclohexane etc. are mentioned.

  The polyimide layer 1 thus obtained may be a single layer or a plurality of layers as described above. However, even if the polyimide layer 1 is composed of a plurality of layers, a raw material is appropriately selected and transparency is obtained. It is possible to make the entire polyimide layer transparent by forming a plurality of layers of polyamic acid that provides the.

  In the present invention, the polyimide film is obtained by forming the polyimide layer 1 on the support substrate 2 and separating it by means such as peeling, but the release surface of the polyimide film after peeling from the support substrate 2 is The surface roughness Ra is preferably 100 nm or less. In order to reduce the surface roughness of the peeling surface, the surface on the support base material 2 side is preferably smooth, and a metal foil and resin composite substrate is used for the support base material 2 as an example. The surface roughness Ra of the heat-resistant polyimide surface can be reduced to 100 nm or less by forming a resin solution of polyamic acid on the foil by a coating method and performing heat treatment for drying and / or curing.

  In the present invention, in addition to the polyimide laminate 10 in which the polyimide layer 1 is laminated on the support substrate 2, as shown in FIG. 1B, a predetermined function is provided on the surface side of the polyimide layer 1 of the polyimide laminate 10. It can also be set as the polyimide laminated body in which the layer 3 was formed. Such a polyimide laminate provides a polyimide film with a functional layer after separating the support substrate on the back side. Examples of the functional layer include a display device such as an organic EL or liquid crystal display, an input device such as a touch panel, a barrier layer for preventing gas and moisture from permeating, a transparent conductive film, and the like. In addition, separation of the support base material 2 after forming the predetermined functional layer 3 may be performed in any step as long as the functional layer is formed.

  In addition, the polyimide laminate 10 of the present invention has an epoxy resin and an acrylic resin on the back side of the support base 2, that is, on the surface of the support base 2 opposite to the interface between the polyimide layer 1 and the support base 2. You may make it further provide the adhesion layer 4 which consists of these. Accordingly, after the polyimide laminate 10 is attached to another member, an operation of separating only the polyimide film or the polyimide film with a functional layer can be performed.

Next, the manufacturing method of the polyimide laminated body of this invention is demonstrated in detail.
A preferred method for producing the polyimide laminate 10 of the present invention is that the glass transition temperature Tg is 300 ° C. or higher, and the long surface having a heat-resistant polyimide surface formed of a heat-resistant polyimide having a surface roughness Ra of 100 nm or less. While transporting the support base material 2 by a roll-to-roll process, a fluorine-containing polyamic acid resin solution is applied onto the heat-resistant polyimide surface of the long support base material 2, and the support base material 2 is 200 ° C. or more. Heat treatment to imidize the polyamic acid to form a polyimide layer 1 having a transmittance of 70% or more in the wavelength region of 440 nm to 780 nm on the support base material 2, and the support base material 2 and the polyimide layer 1. The adhesive strength is 1 N / m or more and 500 N / m or less so that the polyimide film made of the polyimide layer 1 can be separated from the support base 2.

  That is, since the suitable manufacturing method of the polyimide laminated body 10 in this invention enables a roll-to-roll process, the support base material 2 used is elongate, and the glass transition temperature Tg is 300 degreeC. In addition to the above, the surface has a heat-resistant polyimide surface formed of heat-resistant polyimide having a surface roughness Ra of 100 nm or less. In the roll-to-roll process, the support base material 2 is prepared in a state of being wound in a roll shape, and is provided as the support base material 2 by pulling out a part thereof. In addition, it is preferable to apply the same thing as described in invention of the said polyimide laminated body for the polyimide which gives a heat-resistant polyimide surface.

  A polyamic acid resin solution, which is a polyimide precursor, is applied on the heat-resistant polyimide surface of the long support substrate 2 provided in this manner. As the polyamic acid, the above-described fluorine-containing polyamic acid is preferably used.

  After applying the polyamic acid resin solution, the long support base 2 is heated to 150 to 160 ° C. to remove the solvent contained in the resin solution. Imidize. In the heat treatment performed at the time of imidation, it is preferable to raise the temperature continuously or stepwise from a temperature of about 160 ° C. to a temperature of about 350 ° C. after removing the solvent to some extent.

  By the heat treatment, a polyimide laminate 10 in which the polyimide layer 1 is formed on the long support base 2 can be obtained. Here, the polyimide layer 1 on the support substrate 2 becomes the transparent polyimide layer 1 having a transmittance of 70% or more in the wavelength region of 440 nm to 780 nm. In the present invention, in particular in the above heat treatment. It is preferable that the heating time (hereinafter referred to as “high temperature holding time”) in a high temperature heating temperature range from a temperature 20 ° C. lower than the maximum heating temperature at the time of temperature rise (maximum temperature reached) to the maximum temperature reached is within 15 minutes. When the high temperature holding time exceeds 15 minutes, the transparency of the polyimide layer tends to be lowered due to coloring or the like. In order to maintain transparency, it is better that the high temperature holding time is short. However, if the time is too short, the effect of heat treatment may not be sufficiently obtained. The optimum high temperature holding time varies depending on the heating method, the heat capacity of the support substrate 10, the thickness of the polyimide layer 1, etc., but is more preferably 0.5 minutes or more and 5 minutes or less.

  In the polyimide laminate 10 of the present invention, the adhesive strength between the support substrate 2 and the polyimide layer 1 is in the range of 1 N / m or more and 500 N / m or less, and the polyimide film comprising the polyimide layer 1 from the support substrate 2 can be easily obtained. It is in a separable state, and there are no particular restrictions on the form of the separation. For example, the polyimide laminate 10 composed of the support substrate 2 and the polyimide layer 1 may be wound into a roll as it is, and may be in the form of a roll, and is an intermediate step in a roll-to-roll process. After the imidization step is completed, the support substrate 2 and the polyimide layer 1 may be peeled off and separated before the winding step. Alternatively, a sheet-like polyimide laminate 10 cut into a predetermined size may be prepared for each sheet, and the polyimide layer 1 may be peeled off from the support base 2 and separated. In any case, if the functional layer 3 is formed on the surface of the polyimide layer 1, the separated polyimide film can be used as a resin substrate. In particular, before separating the polyimide layer 1 from the support base 2, the functional layer 3 is formed. If it forms, the handleability, dimensional stability, etc. of the said polyimide film can fully be ensured.

  The polyimide laminate 10 of the present invention is characterized in that the adhesive strength between the support substrate 2 and the polyimide layer 1 is low and can be easily separated. In the process of obtaining such a polyimide laminate 10, A polyimide laminate according to the present invention is prepared by temporarily providing a part having a high adhesive strength (over 500 N / m) at a part of the interface between the support base 2 and the polyimide layer 1 and then excising the part. You may get 10. That is, for example, for the purpose of enhancing the shape stability during long-term storage or transportation, the polyimide layer is applied by a method such as applying a polyamic acid solution after intentionally roughening a part of the surface of the support substrate 2. 1 is formed, the adhesive strength of a part of the interface is made higher than most other surfaces (over 500 N / m), and then the part with high adhesive strength is removed by means such as cutting, It can also be set as the polyimide laminated body 10 of this invention.

  Hereinafter, the contents of the present invention will be described more specifically based on examples and the like, but the present invention is not limited to the scope of these examples.

First, the abbreviations of raw material monomers and solvents for synthesizing polyimide, and various physical property measuring methods and conditions in the examples are shown below.
[Abbreviation]
DMAc: N, N-dimethylacetamide PDA: 1,4-phenylenediamine TFMB: 2,2′-bis (trifluoromethyl) -4,4′-diaminobiphenyl DADMB: 4,4′-diamino- 2,2′-dimethylbiphenyl, 1,3-BAB: 1,3-bis (4-aminophenoxy) benzene, BPDA: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 6FDA: 2 , 2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride-PMDA: pyromellitic dianhydride

[Surface roughness (Ra)]
Surface observation was performed in a tapping mode using an atomic force microscope (AFM) “Multi Mode 8” manufactured by Bruker. Observation of a 10 μm square field of view was performed four times, and the average value thereof was obtained. The surface roughness (Ra) represents the arithmetic average roughness (JIS B0601-1991).

[Peelability]
The polyimide laminate was cut into a 50 mm square size as an evaluation sample, and the polyimide layer and the supporting substrate were peeled from one corner. Among those that could be peeled off, those that could be easily peeled without damaging the polyimide layer were marked with ◯, and those that showed film elongation or breakage were marked with ×. In the case of peeling, the adhesive force between the polyimide layer and the supporting substrate was strong, and those that could not be peeled were regarded as unpeelable.

[Peel strength]
A sample obtained by cutting a polyimide laminate into a strip shape having a width of 10 mm was evaluated by measuring peel strength according to a T-peeling test method using a strograph R-1 manufactured by Toyo Seiki Seisakusho.

[Transmissivity (%)]
The average value of the light transmittance from 440 nm to 780 nm was determined for a polyimide film (50 mm × 50 mm) with a U4000 spectrophotometer.

[Glass transition temperature Tg]
The glass transition temperature was measured at a rate of 10 ° C./min from room temperature to 400 ° C. while applying a 1 Hz vibration using a 10 mm wide sample using a viscoelasticity analyzer (RSA-II manufactured by Rheometric Science Effy Co., Ltd.). It was determined from the maximum loss tangent (Tan δ) when the temperature was raised at.

[Coefficient of thermal expansion (CTE)]
Tensile test of polyimide film with a size of 3mm x 15mm in a temperature range from 30 ° C to 260 ° C at a constant heating rate (20 ° C / min) while applying a 5.0g load with a thermomechanical analysis (TMA) device And the coefficient of thermal expansion (× 10 ⁻⁶ / K) was measured from the amount of elongation of the polyimide film with respect to temperature.

Synthesis Example 1 (Polyimide A)
Under a nitrogen stream, 8.00 g of PDA was dissolved in the solvent DMAc while stirring in a 300 ml separable flask. Then 22.00 g of this solution BPDA was added. Thereafter, the solution was stirred at room temperature for 5 hours to conduct a polymerization reaction, and kept for a whole day and night. A viscous polyamic acid solution was obtained, and it was confirmed that polyamic acid A having a high polymerization degree was produced.

Synthesis Example 2 (Polyimide B)
Under a nitrogen stream, 19.11 g of DADMB and 2.92 g of 1,3-BAB were dissolved in the solvent DMAc while stirring in a 300 ml separable flask. To this solution was then added 5.79 g BPDA and 17.17 g PMDA. Thereafter, the solution was stirred at room temperature for 5 hours to conduct a polymerization reaction, and kept for a whole day and night. A viscous polyamic acid solution was obtained, and it was confirmed that polyamic acid B having a high polymerization degree was produced.

Synthesis Example 3 (Polyimide C)
Under a nitrogen stream, 12.08 g of TFMB was dissolved in the solvent DMAc while stirring in a 300 ml separable flask. Next, 6.20 g of PMDA and 4.21 g of 6FDA were added to this solution. Thereafter, the solution was stirred at room temperature for 5 hours to conduct a polymerization reaction, and kept for a whole day and night. A viscous polyamic acid solution was obtained, and it was confirmed that polyamic acid C having a high polymerization degree was produced.

Synthesis Example 4 (Polyimide D)
Under a nitrogen stream, 13.30 g of TFMB was dissolved in the solvent DMAc while stirring in a 300 ml separable flask. Next, 9.20 g of PMDA was added to this solution. Thereafter, the solution was stirred at room temperature for 5 hours to conduct a polymerization reaction, and kept for a whole day and night. A viscous polyamic acid solution was obtained, and it was confirmed that polyamic acid D having a high polymerization degree was produced.

[Example 1]
After applying the polyamic acid A resin solution obtained in Synthesis Example 1 onto an electrolytic copper foil having a thickness of 18 μm, the solvent was removed by heating and drying at 130 ° C. Next, it is imidized by heat treatment from 160 ° C. to 360 ° C. at a heating rate of about 15 ° C./min, and a polyimide layer (surface roughness Ra = 1.3 nm, Tg = 355 ° C.) having a thickness of 25 μm is formed on the copper foil. A formed support substrate was obtained.

  After applying the polyamic acid C resin solution obtained in Synthesis Example 3 to a uniform thickness on the polyimide layer of the obtained support substrate, the solution was heated and dried at 130 ° C. to remove the solvent in the resin solution. Next, the polyamic acid was imidized by heat treatment at a rate of temperature increase of about 20 ° C./min from 160 ° C. to 360 ° C. to obtain a polyimide laminate having a support base on the back side of the polyimide layer. In this state, it was immediately cooled to room temperature, and the polyimide layer was peeled off from the supporting substrate to obtain a transparent polyimide film having a thickness of 25 μm. The peelability between the support substrate and the transparent polyimide film during peeling was good. In the imidization of polyamic acid C, the heating time (high temperature holding time) in a high temperature heating temperature range from a temperature 20 ° C. lower than the highest temperature to the highest temperature, that is, a high temperature holding time from 340 ° C. to 360 ° C. is 1 minute.

  Table 1 shows the characteristics of the supporting base material used in each example, the characteristics of the polyimide layer or polyimide film formed on the supporting base material, and the evaluation results of the polyimide laminate, including the case of Example 1. .

[Example 2]
A polyimide film (Kapton H, manufactured by Toray DuPont Co., Ltd .: surface roughness Ra = 70 nm, Tg = 428 ° C.) having a thickness of 25 μm was used as a supporting substrate, and the polyamic acid C obtained in Synthesis Example 3 was further formed thereon. The resin solution was applied and then dried by heating at 130 ° C. to remove the solvent in the resin solution. Next, heat treatment is performed at a rate of about 20 ° C / min from 160 ° C to 360 ° C to imidize the polyamic acid (high temperature holding time from 340 ° C to 360 ° C is 1 minute), and it is supported on the back side of the polyimide layer It was set as the polyimide laminated body provided with the base material. In this state, it was immediately cooled to room temperature, and the polyimide layer was peeled off from the supporting substrate to obtain a transparent polyimide film having a thickness of 25 μm. The peelability of the supporting substrate and the transparent polyimide film during peeling was good.

[Example 3]
Polyamide acid D resin obtained in Synthesis Example 4 was used on the polyimide film (Upilex S, manufactured by Ube Industries, Ltd .: surface roughness Ra = 15 nm, Tg = 359 ° C.) having a thickness of 25 μm as a supporting substrate. The solution was applied, and then heated and dried at 130 ° C. to remove the solvent in the resin solution. Next, heat treatment is performed at a rate of about 20 ° C / min from 160 ° C to 360 ° C to imidize the polyamic acid (high temperature holding time from 340 ° C to 360 ° C is 1 minute), and it is supported on the back side of the polyimide layer It was set as the polyimide laminated body provided with the base material. In this state, it was immediately cooled to room temperature, and the polyimide layer was peeled off from the supporting substrate to obtain a transparent polyimide film having a thickness of 25 μm. The peelability of the supporting substrate and the transparent polyimide film during peeling was good.

[Example 4]
Polyamide acid D resin obtained in Synthesis Example 4 was used on the polyimide film (Upilex S, manufactured by Ube Industries, Ltd .: surface roughness Ra = 15 nm, Tg = 359 ° C.) having a thickness of 25 μm as a supporting substrate. The solution was applied and then dried by heating at 130 ° C. to remove the solvent in the resin solution. Next, after heating at 150 ° C., 200 ° C., and 250 ° C. for 30 minutes, heating was performed at 350 ° C. for 1 hour to imidize polyamic acid to obtain a polyimide laminate having a support base on the back side of the polyimide layer. In this state, it was immediately cooled to room temperature, and the polyimide layer was peeled off from the supporting substrate to obtain a transparent polyimide film having a thickness of 25 μm. The peelability of the supporting substrate and the transparent polyimide film during peeling was good.

[Comparative Example 1]
Except having used copper foil as a support base material, it heat-processed for application | coating, heat drying, and imidation similarly to Example 1, and obtained the polyimide laminated body. An attempt was made to peel off the polyimide layer from the polyimide laminate, but the adhesive force at the interface between the polyimide layer and the support substrate was strong, and the polyimide could not be peeled from the support substrate.

[Comparative Example 2]
The support base copper foil used in Example 1 was etched to obtain a support base made of a polyimide film. Surface roughness Ra of the copper foil etching surface of this support base material was 180 nm, and Tg was 355 degreeC. A polyimide laminate was obtained in the same manner as in Example 1 except that the polyimide acid C resin solution obtained in Synthesis Example 3 was applied to this surface of the polyimide film as the support substrate. Although an attempt was made to peel off the polyimide layer from the polyimide laminate, the adhesive force at the interface between the polyimide and the support substrate was strong, and the polyimide could not be peeled from the support substrate.

[Comparative Example 3]
A polyimide laminate is obtained in the same manner as in Example 1 except that a 10 mm-thick polyimide substrate (Iupimol, Ube Industries, Ltd .: surface roughness Ra = 160 nm, Tg = 401 ° C.) is used as the support substrate. Then, after cooling to room temperature, the polyimide layer was peeled off from the supporting substrate to obtain a transparent polyimide film having a thickness of 25 μm. When the support substrate and the transparent polyimide film were peeled off, the transparent polyimide film was easily stretched and further ruptured, and the peelability was not good.

[Comparative Example 4]
A polyimide laminate was obtained in the same manner as in Example 3 except that the polyamic acid B resin solution obtained in Synthesis Example 2 was used as the polyamic acid. After cooling to room temperature, the polyimide layer was pulled from the support substrate. The film was peeled off to obtain a transparent polyimide film having a thickness of 25 μm. When the support substrate and the polyimide film were peeled off, the polyimide film was easily stretched and further ruptured, and the peelability was not good.

[Comparative Example 5]
A polyimide laminate was obtained in the same manner as in Comparative Example 4 except that a polyimide film (Kapton H manufactured by Toray DuPont Co., Ltd.) was used as the support substrate. Although an attempt was made to peel off the polyimide layer from the polyimide laminate, the adhesive force at the interface between the polyimide and the support substrate was strong, and the polyimide could not be peeled from the support substrate.

1 Polyimide layer 2 Support base material 3 Functional layer 4 Adhesive layer
10 Polyimide laminate

Claims (12)

A polyimide laminate having a support substrate on the back side of the polyimide layer, the polyimide layer is a single layer or multiple layers, with a layer in contact with at least the supporting substrate is a fluorinated polyimide, 440 nm of the polyimide layer transmittance at 780nm wavelength region from is 70% or more, and the surface of the supporting substrate at the interface between the polyimide layer and the supporting substrate, a glass transition temperature Tg is formed by 300 ° C. or more heat-resistant polyimide In addition, the surface roughness Ra is 100 nm or less, the adhesive strength between the support substrate and the polyimide layer is 1 N / m or more and 500 N / m or less, and the polyimide film composed of the polyimide layer can be separated from the support substrate. A polyimide laminate characterized by the above. The polyimide laminate according to claim 1, wherein the adhesive strength between the support substrate and the polyimide layer is 5 N / m or more and 300 N / m or less . The polyimide laminate according to claim 1 or 2, wherein the heat-resistant polyimide in the support substrate is a polyimide having the following structural units.

  The polyimide laminate according to any one of claims 1 to 3, wherein the polyimide layer has a thermal expansion coefficient of 15 ppm / K or less.   The polyimide laminate according to any one of claims 1 to 4, wherein the polyimide layer has a thickness of 3 µm to 50 µm, and the support base material has a thickness of 10 µm to 100 µm.   The polyimide laminate according to any one of claims 1 to 5, wherein the release surface of the polyimide film after peeling from the support substrate has a surface roughness Ra of 100 nm or less.   The polyimide laminate according to any one of claims 1 to 6, wherein after forming a predetermined functional layer on the surface side of the polyimide layer, the support substrate on the back side is separated and used.   The polyimide laminated body in any one of Claims 1-7 further equipped with the adhesion layer in the back side of a support base material.   A method for producing a polyimide laminate comprising a support base on the back side of a polyimide layer, wherein the glass transition temperature Tg is 300 ° C. or higher and the surface roughness Ra is 100 nm or less and is formed by a heat resistant polyimide. While transporting a long support substrate having a polyimide surface by a roll-to-roll process, a fluorine-containing polyamic acid resin solution is applied onto the heat-resistant polyimide surface of the long support substrate, The whole material is heat-treated at 200 ° C. or more to imidize polyamic acid, and a polyimide layer having a transmittance of 70% or more in the wavelength region of 440 nm to 780 nm is formed on the support substrate, and the support substrate and polyimide The adhesive strength with the layer is 1 N / m or more and 500 N / m or less, and the polyimide film composed of the polyimide layer can be separated from the support substrate. Method for producing a polyimide laminate that.   The polyimide laminate according to claim 9, wherein the heat treatment condition of the polyamic acid is within 15 minutes in a high-temperature heating temperature range from a temperature 20 ° C lower than the highest temperature achieved during heating and heating to the highest temperature. Manufacturing method. The manufacturing method of the polyimide laminated body of Claim 9 or 10 whose heat resistant polyimide which forms the heat resistant polyimide surface in a support base material is a polyimide which has the following structural unit.

  The manufacturing method of the polyimide film characterized by isolate | separating a polyimide layer from the polyimide laminated body obtained by the method as described in any one of Claims 9-11.

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